Disk storage devices are known which use magnetic recording media represented by hard disk drives (HDD). The storage capacities of disk storage devices have been increasing year by year. In connection with this, the density of tracks in disks has increased, and the adverse effect of (Adjacent Track Interference) has been more and more significant.
For example, when data is written to a target track in a disk, a magnetic field leaking from the target track may destroy data in a track located adjacent to the target track.
Furthermore, in recent years, research and development has been promoted for shingled write recording, which is excellent in enabling an increase in the density of tracks. The shingled write recording is a scheme in which data is written such that relevant tracks partly overlap. That is, no gap is created between the tracks, thus making the adverse effect of ATI much more significant.
When tracks are more densely formed in order to increase storage capacity, errors occur more frequently. For example, data is written to tracks in units of sectors, and if a read of data written to a certain sector fails, this particular sector is managed as a defective sector. The defective sector is excluded from the subsequent data write target. Frequent occurrence of defective sectors may reduce the storage capacity.